Issues in wordpress with permalinks and archives

I have being trying to change my permalinks in wordpress to make them much more attractive than the default. I used the /%year%/%monthnum%/%postname%/ option. All of my posts copied over fine BUT when I click on archives it retruns a forbidden 403 error.

(in the meantime I have changed the permalinks back to the ugly default version)

I have chmod 666 my htaccess file as suggested but this makes no difference. This is what my htaccess file looks like at present;

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

can anyone suggest anything else, i’m so fed up with it but i’m loving the wordpress blog format.

Cheers